Testing Meson Portal Dark Sector Solutions to the MiniBooNE Anomaly at CCM

TL;DR

This paper explores dark sector models involving long-lived particles from meson decays as an explanation for the MiniBooNE anomaly, analyzing their compatibility with existing constraints and future experimental sensitivities.

Contribution

It extends phenomenological models of meson decays to include long-lived particles, providing a comprehensive analysis of their potential to explain the MiniBooNE excess and be tested by CCM and other experiments.

Findings

Models can be compatible with LSND, KARMEN, MicroBooNE constraints.

Sensitivity estimates for CCM experiment to detect these scenarios.

Updated predictions for MicroBooNE future sensitivity.

Abstract

A solution to the MiniBooNE excess invoking rare three-body decays of the charged pions and kaons to new states in the MeV mass scale was recently proposed as a dark-sector explanation. This class of solution illuminates the fact that, while the charged pions were focused in the target-mode run, their decay products were isotropically suppressed in the beam-dump-mode run in which no excess was observed. This suggests a new physics solution correlated to the mesonic sector. We investigate an extended set of phenomenological models that can explain the MiniBooNE excess as a dark sector solution, utilizing long-lived particles that might be produced in the three-body decays of the charged mesons and the two-body anomalous decays of the neutral mesons. Over a broad set of interactions with the long-lived particles, we show that these scenarios can be compatible with constraints from LSND, KARMEN, and MicroBooNE, and evaluate the sensitivity of the ongoing and future data taken by the Coherent CAPTAIN Mills experiment (CCM) to a potential discovery in this parameter space. See addendum for updated predictions for future MicroBooNE sensitivity.